New ATLAS publication

Measurement of the tttt production cross section in pp collisions at sqrt(s)=13 TeV with the ATLAS detector” has been submitted to JHEP. Members of the IFAE-ATLAS team (Aurelio Juste, Nicola Orlando, and Anil Sonay) have played a leading role in this publication, from designing the analysis strategy to the final multivariate technique and statistical analysis employed.

This paper presents a measurement of the four-top-quark production cross section in final states with a single lepton or an opposite-sign lepton pair in association with multiple jets using the full Run 2 dataset collected with the ATLAS detector. With four top quarks produced per event, this is a very rare Standard Model process with a predicted cross section of only 12 fb, and thus is very sensitive to beyond-the-SM (BSM) contributions. A sophisticated event categorization and multivariate technique is used to discriminate signal from background events. The result of this analysis is combined with a previous measurement in multilepton final states. The combined cross section is measured to be a factor of two higher than the SM prediction, although compatible with it within 2.0 standard deviations. The corresponding observed (expected) signal significance is .7 (2.6) standard deviations over the background-only prediction.

The IFAE team is currently working on an improved analysis targeting BSM production of four-top-quark events. Stay tuned!

More information on the ATLAS Physics Briefing


Latest Group News


ATLAS pixels group milestone towards ITk module production

April 6, 2022

IFAE´s ATLAS pixels group has achieved a new milestone towards the ATLAS ITk Pixel module production.

New Member

New member of the ATLAS group

February 16, 2022

Judita Mamužić has just started as a new postdoc of the ATLAS Group.


New HGTD project milestone

February 9, 2022

The first results of charge collection in ALTIROC2 prototypes for HGTD have been carried out at IFAE.